The present invention relates to apparatus for uniting webs of flexible material, especially for splicing photographic films to each other as well as to similar webs or strips. More particularly, the invention relates to apparatus for splicing photographic films to each other and/or to strips or webs (hereinafter called tapes) which are used to facilitate threading of films through various units in a photographic processing laboratory and/or to attach photographic films to the cores of reels or spools.
In order to enhance the output of modern photographic processing laboratories, it is customary to connect a large number of exposed photographic customer films end-to-end so that the films form a long web which is thereupon transported through the developing machine. As a rule, flexible tapes are connected to the leader as well as to the trailing end of each web. The front tape facilitates threading of the leader of the web through a developing or other machine in the processing laboratory and the attachment of the web to the core of a reel or spool. The purpose of the rear tape is to facilitate the attachment to the core of a reel on which the web is to be stored or to facilitate attachment of the web to the next web.
The output of the developing machine is increased if the web consists of a very large number of spliced-together exposed photographic films, i.e., if the number of interruptions which are necessary to thread the leader of a fresh web through the developing machine is reduced to a minimum. For example, a receptacle for storage of exposed but undeveloped photographic films can accommodate between 300 and 600 meters of film, i.e., at least 600-700 discrete films. On the other hand, the manipulation of extremely long webs of spliced-together photographic films in the copying machine, in the severing unit which subdivides the web into discrete films or into groups of film sections each belonging to a different customer, in the marking unit which provides the films with indicia in the form of notches, perforations or the like, and/or in the order center wherein the customer films and the associated prints are introduced into envelopes for shipment or to for pickup by customers or dealers adversely affects the output of such units. The optimum length of webs which are to be processed in various units following the developing machine is between 60 and 120 meters. Therefore, a long web which has been transported through the developing machine (e.g., a web having a length of 300-600 meters) is normally subdivided into shorter webs each of which has a length in the range of 60-120 meters. This entails the attachment of an additional tape to the trailing end of the foremost shorter web, to the leader of the rearmost shorter web as well to the leader and trailing end of the rearmost shorter web as well as to the leader and trailing end of each intermediate shorter web.
German Offenlegungsschrift No. 2,132,573 (See U.S. Pat. No. 3,779,837) discloses a splicing apparatus having means for supporting a reel of convoluted threading tape portions of which can be attached to the leaders and trailing ends of discrete webs each of which consists of several films spliced together end-to-end. It has been found that the manipulation of tape (especially proper positioning of its leader with respect to the trailing end of a web as well as proper positioning of the trailing end of a separated portion of tape relative to the leader of the next-following web) presents many problems, mainly because the tape does not exhibit perforations or other indicia which would allow for automatic stoppage of the leader of tape or the trailing end of a separated portion of tape in an optimum position relative to the trailing end or leader of a web of photographic films. In other words, it is difficult to properly position the leader of tape or the trailing end of a portion of tape at the splicing station where the tape is to be united with the trailing end or with the leader of a web. As a rule, proper positioning of tape involves placing the front edge face of the leader or the rear edge face of the trailing end at the center of the splicing station. If the leader and/or trailing end of the tape is not in an optimum position, the splice between the tape and the web is likely to be defective, i.e., the tape is likely to become separated from the web. This invariably entails lengthy interruptions in operation of the respective unit in the processing laboratory.